1. Field of the Invention
The present invention relates to a solid-state image pickup device, a method of controlling a solid-state image pickup device, and an image pickup device.
Priority is claimed on Japanese Patent Application No. 2012-254093, filed Nov. 20, 2012, the content of which is incorporated herein by reference.
2. Description of the Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
In recent years, complementary metal-oxide semiconductor (CMOS) solid-state image pickup devices (hereinafter, referred to as a “MOS-type solid-state image pickup devices) have gained attention and been put to practical use.
This MOS-type solid-state image pickup device can be driven by a single power source, unlike a charge-coupled device (CCD)-type solid-state image pickup device. Also, while a dedicated fabrication process is required for a CCD-type solid-state image pickup device, since it is possible to fabricate a MOS-type solid-state image pickup device using the same fabrication process as for other LSI circuits, compatibility with system-on-chip (SOC) fabrication is easy, thus enabling multi-functionality of a solid-state image pickup device.
Also, since a MOS-type solid-state image pickup device amplifies the signal charge in a pixel by providing an amplification circuit in each pixel, it has a constitution that is hardly influenced by noise from the signal transmission route. Moreover, selecting and extracting the signal charge of each pixel (selection system) is possible, and so in principal it is characterized by being able to freely control the signal storage time and readout sequence for every pixel.
Conventionally, a digital single-lens reflex camera is an image pickup device that is equipped with a MOS-type solid-state image pickup device (hereinafter also called a “solid-state image pickup device”).
In a conventional digital single-lens reflex camera, subject information is obtained by causing the subject light (incident light) that has passed through the lens to be made incident on the solid-state image pickup device, and guiding the subject light to, for example, sensors for autofocus (AF) such as phase-detection AF sensors using a mirror.
However, so-called mirrorless cameras that are not provided with the aforementioned mirror are now gaining popularity. In a mirrorless camera, it is not possible to guide the subject light to the phase-detection AF sensors by a mirror in the manner of a conventional digital single-lens reflex camera. For this reason, in the AF system in a mirrorless camera, there is no choice but to adopt the so-called contrast-detection AF system that performs autofocus control based on pixel signals that are output from the solid-state image pickup device.
However, with regard to the autofocus control in the contrast-detection AF system, generally there is the problem of the AF operation being slow in comparison to the autofocus control of a system that uses a phase-detection AF sensor.
As art for solving this kind of problem, Japanese Unexamined Patent Application, First Publication No. 2011-171749 discloses an image pickup device in which pixels for phase-detection AF that acquire subject information for performing autofocus control in addition to ordinary pixels for acquiring an image are provided in an effective pixel area of a solid-state image pickup device.